Hypoventilation

About: Hypoventilation is a research topic. Over the lifetime, 1772 publications have been published within this topic receiving 40799 citations. The topic is also known as: respiratory depression.

Benefit-risk assessment of transdermal fentanyl for the treatment of chronic pain

Abstract: Transdermal fentanyl is effective and well tolerated for the treatment of chronic pain caused by malignancy and non-malignant conditions when administered according to the manufacturer’s recommendations. Compared with oral opioids, the advantages of transdermal fentanyl include a lower incidence and impact of adverse effects (constipation, nausea and vomiting, and daytime drowsiness), a higher degree of patient satisfaction, improved quality of life, improved convenience and compliance resulting from administration every 72 hours, and decreased use of rescue medication. Transdermal fentanyl is a useful analgesic for cancer patients who are unable to swallow or have gastrointestinal problems. Transdermal fentanyl forms a depot within the upper skin layers before entering the microcirculation. Therapeutic blood levels are attained 12–16 hours after patch application and decrease slowly with a half-life of 16–22 hours following removal. Patients with chronic pain should be titrated to adequate relief with short-acting oral or parenteral opioids prior to the initiation of transdermal fentanyl in order to prevent exacerbations of pain or opioid-related adverse effects. Transdermal fentanyl can then be initiated based on the 24-hour opioid requirement once adequate analgesia has been achieved. The prolonged elimination of transdermal fentanyl can become problematic if patients develop opioid-related adverse effects, especially hypoventilation. Adverse effects do not improve immediately after patch removal and may take many hours to resolve. Patients who experience opioid-related toxicity associated with respiratory depression should be treated immediately with an opioid antagonist such as naloxone and closely monitored for at least 24 hours. Because of the short half-life of naloxone, sequential doses or a continuous infusion of the opioid antagonist may be necessary. Transdermal fentanyl should be administered cautiously to patients with pre-existing conditions such as emphysema that may predispose them to the development of hypoventilation. Transdermal fentanyl is indicated only for patients who require continuous opioid administration for the treatment of chronic pain that cannot be managed with other medications. It is contraindicated in the management of acute and postoperative pain, as pain may decrease more rapidly in these circumstances than fentanyl blood levels can be adjusted, leading to the development of life-threatening hypoventilation. Cognitive and physical impairments such as confusion and abnormal co-ordination can occur with transdermal fentanyl. Therefore, patients should be instructed to refrain from driving or operating machinery immediately following the initiation of transdermal fentanyl, or after any dosage increase. Patients may resume such activities once the absence of these potential adverse effects is documented.

Central apnea and acute cardiac ischemia in a sheep model of epileptic sudden death

Abstract: The etiology of sudden death in patients with epilepsy remains unclear. Previous studies in a well-established sheep model of status epilepticus showed that more than one-third of the unsedated animals died within 5 minutes of seizure onset due to hypoventilation. The relative contributions of airway obstruction and central hypoventilation could not be determined because airway flow and respiratory effort were not monitored. In this study, status epilepticus was induced in unsedated sheep with tracheostomies monitored by electrocardiography, electroencephalography, arterial line, serial blood gases, and airway flowmeter. All 8 animals demonstrated central apnea and hypoventilation, which resulted in the death of 1 and contributed to the death of another. A third animal died of acute heart failure within 2 minutes of seizure onset, accompanied by a large septal myocardial hemorrhage, contraction bands, and signs of global cardiac ischemia. More subtle contraction bands, subendocardial hemorrhage, and signs of acute myocardial ischemia were seen in other animals as well, none of which died of cardiac causes. Malignant arrhythmia was not seen in any of the sheep. Central hypoventilation and apnea accompany generalized status epilepticus and may be an important cause of sudden death in epileptics. Acute cardiac failure may also be a cause of epileptic sudden death.

Respiratory Management in the Patient with Spinal Cord Injury

Abstract: Spinal cord injuries (SCIs) often lead to impairment of the respiratory system and, consequently, restrictive respiratory changes. Paresis or paralysis of the respiratory muscles can lead to respiratory insufficiency, which is dependent on the level and completeness of the injury. Respiratory complications include hypoventilation, a reduction in surfactant production, mucus plugging, atelectasis, and pneumonia. Vital capacity (VC) is an indicator of overall pulmonary function; patients with severely impaired VC may require assisted ventilation. It is best to proceed with intubation under controlled circumstances rather than waiting until the condition becomes an emergency. Mechanical ventilation can adversely affect the structure and function of the diaphragm. Early tracheostomy following short orotracheal intubation is probably beneficial in selected patients. Weaning should start as soon as possible, and the best modality is progressive ventilator-free breathing (PVFB). Appropriate candidates can sometimes be freed from mechanical ventilation by electrical stimulation. Respiratory muscle training regimens may improve patients' inspiratory function following a SCI.

Unilateral hypoventilation in man during temporary occlusion of one pulmonary artery

Abstract: Occlusion of the right or left pulmonary artery forces the opposite lung to perform the total gas exchange. The alveolar ventilation of the one functioning lung must increase if it is to maintain normal arterial blood oxygen and carbon dioxide tensions (1). One would predict that total ventilation would increase about 80 to 90 per cent to achieve the necessary increase in alveolar ventilation. S6derholm, however, found only a 30 per cent increase in total ventilation when one pulmonary artery was occluded even though arterial blood oxygen saturation, carbon dioxide tension and pH did not change (2). Other investigators (3, 4) have noted even smaller changes in total ventilation during temporary unilateral pulmonary arterial occlusion (TUPAO). If tidal volume, frequency of breathing and oxygen consumption remain the same, these findings could be explained only if some or all of the ventilation of the nonperfused lung were shifted to the functioning lung. Moore, Humphreys and Cochran (5) have shown that such a shift of ventilation did occur in most dogs when one pulmonary artery was occluded by tightening a ligature brought out through the chest wall. They attributed this shift to a loss of erectile support of the vascular bed in the lung. Venrath, Rotthoff, Valentin and Bolt (6) also reported a redistribution of ventilation in dogs when one pulmonary artery was occluded by a balloon. They believed that the shift was caused by the low CO, on the nonperfused side, which is consistent with Nisell's observation (7) that bronchoconstriction occurred in excised cat lungs

Use of a measurement of pulmonary hyperinflation to control the level of mechanical ventilation in patients with acute severe asthma.

Abstract: Mechanical ventilation causes significant morbidity and mortality in patients with severe asthma. Hypoventilation may reduce this morbidity and mortality, but indicators to guide the degree of hypoventilation are unclear. We used a measure of pulmonary hyperinflation to assess the degree of airflow obstruction and to guide the extent and duration of hypoventilation. Ten patients who required mechanical ventilation for acute severe asthma were studied. All were sedated, paralyzed, and given an initial minute ventilation (e) of 200 ml/kg/min. End-inspiratory lung volume (Vei) above FRC was measured from the total exhaled gas volume during 40 to 60 s of apnea. Vei was used to regulate e to a safe level (esafe), irrespective of PaCO2, by reducing the rate when Vei was > 20 ml/kg and increasing it when Vei was < 20 ml/kg. Each patient was weaned when esafe resulted in PaCO2 ⩽ 40 mm Hg (the weaning point). FRC was measured by computer analysis of anterior and lateral chest radiographs taken at the end of apnea....